As the title says, is a readback required? I've heard some people say that it's not required, while some others say we should readback our call sign only. Some even say just push the transmission knob twice to inform the controller that we are acknowledging.

Which one is the correct action and what are the references or publications?enter image description hereenter image description here

  • $\begingroup$ Which country are you asking about? Requirements, regulations and local practices can be different in different parts of the world. $\endgroup$
    – Pondlife
    Commented Apr 12, 2019 at 20:04
  • $\begingroup$ I'm not sure that this is a dupe. The question @fooot linked to asks "what does it mean" but this question asks "is a readback required". Those seem like quite different questions to me. $\endgroup$
    – Pondlife
    Commented Apr 13, 2019 at 2:12
  • 1
    $\begingroup$ @Pondlife the linked question also includes "what would be the appropriate responses" $\endgroup$
    – fooot
    Commented Apr 13, 2019 at 2:23

2 Answers 2


No. It is an information by the controller to let you know that you have been heard & identified. As he doesn't pass any relevant or critical information, there is no need to readback. The same goes with e.g. wind information given by ATC.

  • $\begingroup$ That’s not how we do it in US airspace. Do you have a source for your assertion? $\endgroup$
    – JScarry
    Commented Apr 12, 2019 at 18:39
  • 1
    $\begingroup$ In the US (Boston, MA, area), it usually comes across as "Nxxxxx, radar contact, xx miles south of (location, like the airport you just departed from), altimeter xx.xx", and we would reply, "xx.xx, Nxxxxx". $\endgroup$
    – CrossRoads
    Commented Apr 12, 2019 at 23:12
  • $\begingroup$ In my case, when I've been hand over to SHANGHAI CTRL, which is in CHINA, the controller only acknowledged with "callsign, SHANGHAI CTRL, radar contact." most of time. According to DOC. 4444, it mentions only INSTRUCTION, CLEARANCE, ALTIMETER SETTING, SSR CODE, etc., that need to read back. What confuse me is that if I don't read back, some controller will say again in case I don't get them. However, if I'd like to read back, I can't find the reference that I can read back with call sign or simply click mic twice. $\endgroup$
    – Robert Lo
    Commented Apr 13, 2019 at 2:45
  • $\begingroup$ @JScarry If the ATC passes any other information such as altimeter right after the radar contact phrase, then you usually readback as the call includes critical information. However, here in Europe, ATC very rarely passes any information that might be important within the radar contact acknowledgement. $\endgroup$
    – Windshear
    Commented Apr 13, 2019 at 12:37
  • $\begingroup$ @JScarry - do you have a source for your assertion? Proving a negative is hard, and I promise you most controllers don't care if someone doesn't say anything after "radar contact" if no further instructions are provided. (In the US). $\endgroup$ Commented Apr 13, 2019 at 23:42

"Reading back", i.e. repeating what ATC said to you, is only required for clearances and hold-short instructions, when it's critical that ATC knows you understood them. A simple "radar contact" message is neither.

Most other things, you just "acknowledge", which can be done by saying your callsign or clicking the mic twice. (ATC usually adds "roger", which is a holdover from Morse code operators using "R" as a shorthand for "received"; most pilots don't bother.) This is done so ATC knows you heard them, but for non-critical things that don't require a readback. If you don't acknowledge, ATC may keep repeating it until you do, which is annoying both to them and to everyone else on the frequency; acknowledge promptly so they can move on.

However, when they say "radar contact", they will usually include additional information such as the position of the contact, altitude, etc. You only need one acknowledgement for the entire message. Note that if the position or altitude they say is incorrect, you really need to tell them that, because it means they're looking at the wrong radar target--and that could get you or someone else killed. Acknowledging is an implicit confirmation that they're looking at the correct target.

If they give instructions or ask questions as part of the same message, then you would reply to those as you normally would; you don't need to separately acknowledge the "radar contact" or other informational parts because it's assumed you heard them if you're replying to other parts of the same message.

  • $\begingroup$ To add, if you are calling an approach controller and they issue a squawk, then call "radar contact," no follow-up is required. If you are departing a towered airport and are instructed to contact departure—and you do—and they say "radar contact"—THEN you should respond with some sort of acknowledgement, even just your callsign, to close the two-way communications loop (now each party is sure that the other was able to hear them). $\endgroup$
    – randomhead
    Commented Mar 9, 2021 at 21:38

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